Dental and surgical percussion tool



March 1952 F. M. HUFNAGEL DENTAL AND SURGICAL PERCUSSION TOOL Filed April 21, 1947 FRED M. HUFNAGEL AAnnA 141mm:

.ISEEEE:========= Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE 15 Claims.

My invention relates to dental and surgical percussion tools, and included in the objects of my invention are:

First, to provide a tool of this character which is of pencil-form so as to be held between the fingers of a dentist or surgeon, and which is arranged to carry various tool tips; for example, compactors or dental foil condensers of appropriate shapes for the purpose of condensing gold or silver fillings into tooth cavities; or various chisels for the purpose of chipping bone or breaking teeth in the course of dental surgery, or in other branches of surgery in which the operation requires the careful and controlled chipping of bone structure.

Second, to provide a percussion tool for dentists and surgeons wherein the frequency or rate of impact and the magnitude of impact may be readily adjusted over a wide range and accurately controlled to meet all conditions of use.

Third, to provide an electrical percussion tool of this class which incorporates a novelly arranged switch operated by pressure applied to the tool tip as well as means for adjusting or predetermining the pressure required against the tool tip to close the switch so that the tool tip may be pressed against the surface to be acted upon with a predetermined force before the switch is closed and the tool is operated thus providing a percussion tool which is inactive or inert except when actually in position for use.

Fourth, to provide a dental or surgical percussion tool which incorporates a novelly arranged head whereby percussion tool tips may be disposed in predetermined angular relation to the axis of the tool, and readily interchanged as needed.

With the foregoing and other objects in view, reference is directed to the accompanying drawings in which:

Figure 1 is an enlarged longitudinal sectional view of my dental and surgical percussion tool.

Figure 2 is a perspective view of the cylinder or core of the tool.

Figure 3 is a perspective view of the movable switch element.

Figure 4 is a further enlarged transverse sectional view through 44 of Figure 1.

Figure 5 is a transverse sectional view through 5-5 of Figure 1.

Figure 6 is a fragmentary longitudinal sectional view showing the upper portion of the tool and at an angle to the axis of the handle of the tool.

Figure 8 is an enlarged sectional view of the operating end of the head structure shown in Figure 7.

Figure 9 is a further enlarged transverse sectional view through 9-9 of Figure 8.

Figures 10, 11 and 12 are wiring diagrams illustrating different means for controlling the operation of the percussion tool.

My dental and surgical percussion tool includes a cylinder or tube I of non-magnetic material around which is mounted a pair of solenoid coils 2 and 3. Between and at the ends of the coils are spacer rings 4 of magnetic material. The coils are enclosed by a sleeve 5, also of magnetic material.

The lower end of the cylinder I, as well as the sleeve 5, extend beyond the solenoid coils. The extended portion of the cylinder I is externally threaded and receives a fixed contact plate 6 which overlies the adjacent spacer ring 4. The contact plate carries one or more contacts l which are electrically connected to the solenoid coils in a manner to be described hereinafter.

Slidably mounted within the extended lower end of the sleeve 5 and surrounding the cylinder I is a switch collar 8 which carries a contact ring 9. The switch collar is limited in downward or outward movement by means of a spacer nut I0, threaded onto the cylinder I.

The threaded lower end of the cylinder I protrudes beyond the sleeve 5 and receives an adaptor head piece II. The head piece II is tapered and may be knurled or otherwise arranged to form a finger grip. The head piece I I is provided with a central bore which continues axially from the cylinder I and which receives at its extended end a bearing tip I2.

Slidably fitted within the cylinder I is an anvil I3 having a cushion M at its upper end. The anvil I3 is provided with a cross pin I5 which extends diametrically through suitable clearance slots provided in the walls of the cylinder I. The extremities of the cross pin I5 extend into diametrically disposed holes provided in the switch collar 8. The extended or lower end of the anvil I3 is reduced in diameter and receives a small chuck I6 in the form of a collar or sleeve having an axially split lower end. Any one of a selected series of tool elements I1 is adapted to be inserted through the bearing tip I2 and frictionally engaged by the chuck I6.

The lower extremity of the cylinder I is provided with a fixed collar Ia and the reduced portion of the anvil I3 is threaded to receive an adjustable collar l3a. A spring 18 is interposed between the collars la and I341. Another spring I9 is interposed between the switch collar 8 and the spacer nut I0. Operation of the switch collar and the function of the springs l3 and it will be described hereinafter.

The cylinder I receives above the anvil 53, a hammer or armature 28 of magnetic material which is caused to reciprocate by alternate energizing of the solenoid coils 2 and 3.

The upper end of the cylinder extends above the solenoid coils and is provided with a cap nut 2|. Between the cap nut and upper end of the sleeve is rotatably mounted an elongated collar 22, the lower portion of which is internally threaded. The threads of the collar 22 engage a traveler nut 23 of T shaped cross section the stem of which extends through slots 24 provided in the cylinder I. Attached to the traveler nut 23 is a cushion spring 25. The traveler nut and its cushion spring form an adjustable and yieldable stop limiting upward movement of the hammer-armature 20.

Above the upper limit of adjustment of the traveler nut 23, the cylinder is provided with a side slot 26. Lead wires, preferably three in number, forming a cable 27 pass downwardly through the cap nut 2i into the cylinder 9, laterally through the slot 26, downwardly through the cut-out portions of the traveler nut 25 to the solenoid coils 2 and 3 and to the contacts I. As shown in the diagrammatical views, Figures 10, 11 and 12, one lead is common to the two solenoid coils and is in series with the contacts 1. The other leads are connected individually to the solenoid coils and to an alternator switch 2 3 in the form of a single-pole double-throw switch. Alternating current or direct current is supplied to the common contact of the switch 23 and the common lead of the coils 2 and 3. Interposed in the circuit which energizes the solenoid coils is a voltage regulator 29 for the purpose of adjusting the impulse produced by the solenoid coils on the hammer-armature 2d.

The alternator switch 28 may be operated by various means, for example, as shown in Figure 10, the common or moving contact of the alternator switch 23 is actuated in one direction by a magnetic relay coil 30 and in the other direction by a spring. The relay coil 30 is alternately energized and de-energized by .a grid controlled electron discharge device 3!. The coil is connected serially with the anode and cathode of the device 3| and a space current source which may be either A. C. or D. C. The control grid of the device is connected to the cathode through parallel circuits containing a condenser 32 and a resistance 33 either or both of which may be adjustable. In addition, the control grid and cathode are connected through a normally open auxiliary switch 36a mechanically connected with the alternator switch 28 and a D. C. source 301), its positive terminal being connected with the cathode and its negative terminal being connected with the control grid whereby closure of the normally open auxiliary switch 39a occasioned by energizing the relay coil 39, renders the control grid suificiently negative to decrease the fiow of space current through the relay coil Sil to the extent that the switch 36a is opened. Thereafter, switch 30a remains open until a substantial amount of stored energy in condenser 32 is dissipated at the variable rate determined by the adjustment of the resistance, after which the relay coil is sufficiently energized to close switch 30a to complete a cycle of operation. A wide range of adjustment of the frequency of operation of the hammer-armature is obtained by this arrangement.

An alternative control for the alternator switch is shown in Figure 11. This includes a cam 34 driven by a variable speed motor 35, the speed of which is determined by a variable resistance 36. The cam 34 engages a lever carrying the common contact of the alternator switch and is so shaped as to close the circuit first to one, then the other of the solenoid coils 2 and 3.

A further modified control is shown in Fi u e 12 wherein the common contact of the alternator switch is mounted on a vibrating reed 31. Movement of the reed is maintained by opposed oscillating coils 33 which may be connected in parallel with the coils 2 and 3. The period of vibration of the reed 3? is determined by a weight 39.

Operation of my dental and surgical percussion tool is as follows:

Prior to use of the tool, the alternator switch 28 is set into operation at the desired frequency and the voltage regulator 29 for the solenoidcoils 2 and 3 is adjusted to impart the desired energy to the hammer-armature 25. Alternatively, the collar 22 may be rotated to adjust the position of the cushion spring 25 thereby to limit the length of travel of the hammer-armature 20. The switch comprising the contacts I and contact ring 9 must first be closed before the hammer-armature an is reciprocated.

This control switch is closed by applying pressure to the end of the tool element H. The amount of pressure required is determined by the resultant force exerted by the two springs 18 and IS. The spring 18 is stronger than the spring l9 and its force is exerted in opposition to end pressure on the tool element ll. Upon closing the contacts 1, the solenoid coils 2 and dare alternately energized, causing the hammer-armature 2'53 to reciprocate and rapidly strike the anvil it. The impact of the hammer is transferred by the anvil to the tool element [1.

The actual movement of the anvil I3 is quite slight; that is, less than the clearance between the extremities of the cross pin 55 and the holes in the walls of the contact ring 9 and thus form a lost motion device. Furthermore, the extremities of the pins bear, if at all, upwardly against the contact ring or movable element of the switch as long as the required pressure is maintained on the tool element ll. Conse quently, the spring [9 maintains the contact ring 9 across the contacts 7 even throughout movement of the anvil.

It should be pointed out that it is highly desirable in the operation of the percussion tool that pressure must be maintained by the tool element I? on the surface Whichis to receive the impacts, to transmit eifectively the percussion blow of the hammer and to render certain that the blows are delivered to precisely the right spot.

Other advantages are gained, for example, the tool element may be one of the several types and shapes of condensers used to condense or pack filling such as gold leaf filling or silver alloy into a cavity. It is customary for a dentist to transport increments of the filling from his supply to the cavity by means of the extremity of the tool element itself. This would not be pos sible if the tool element continuously vibrated. Instead, the tool is automatically brought into op ration. w en t e t ol e ement is pressed against the filling material and automatically ceases operation when pressure is relieved. i

It should be further observed that my percussion tool is not limited to such use, but that other tool elements such as chisels or other tooth or bone chipping tools may be employed. For example, by the use of appropriate chisel elements a tooth may be split or the bone chipped to facilitate removal of a tooth such as an impacted wisdom tooth. In such use, the voltage regulator 29 or the collar 22, or both, may be adjusted to increase the impact force delivered to the chisel element. In addition, the collar 13a may be ad justed to increase the force of the spring it thereby to increase the initial pressure required on the tool element before the contacts 1 are closed.

It should be noted that Figure l is an enlarged view and that the entire tool is no larger than necessary to fit comfortably in the dentists or surgeons hand and that only one hand is needed for manipulation of the tool even in difiicult bone surgery cases. While reference has been made to surgery involving the jaw or mouth, my percussion tool also has application in other surgical operations such as nasal or sinus operations.

It is not necessary for operation of the tool that the tool element be in axial alignment with the anvil. In this connection, attention is directed to Figures 7, 8 and 9 wherein a modified head structure is shown so arranged that impact may be directed in angular relation to the anvil. This is accomplished by an adaptor 4B which is at tached to the cylinder l in place of the head piece II. The adaptor terminates in a head 4| dis posed at an appropriate angle. The head 4| is provided with a socket 42 which is intersected by a bore 43 extending axially through the adaptor 40. The bore 43 receives a pin 44, the inner end of which fits into the chuck [5. The extended end of the pin 44 is conical in form and projects into the socket 42.

The socket 42 receives a tool element 45 having a cylindrical shank 45. Formed in the cylindrical shank 45 is a lateral recess 4'? which admits the extremity of the pin 44. The lateral recess 41 may be just sufllcient to accommodate the pin 44 so that the pin not only retains the tool element in the socket 42 but also prevents rotation. Inasmuch as it is sometimes desirable to setthe tool element 45 in different angular positions, the recess 41 may extend circumferentially to permit limited rotation of the tool element. In such case the tool element may be set into one of several positions by means of a key 48 extending from the shank 46 and adapted to fit into one of several slots 49 cut into the extremity of the head 4!. The engaging faces of the pin 44 and surfaces 4'! are such that inward pressure on the extremity of the tool element 45 exerts an axial pressure on the pin 44 sufficient to close the contact 1. Under such conditions, impact on the pin 44 is transmitted to the tool element 45.

Many other embodiments of the invention may be resorted to without departing from the spirit of the invention.

I claim:

1. A dental or surgical percussion tool comprising: a body; a hammer-armature mounted for reciprocation on said body; solenoid coil means for reciprocating said hammer-armature; an anvil and tool tip positioned for engagement by said hammer-armature and mounted for limited reciprocation on said body; a control switch for said solenoid coil means operated by movement of said tool tip relative to said body in response to pressure thereof against a surface; and yieldable means adapted to maintain said switch closed during repeated impacts of said hammer armature and reciprocations of said anvil and tool.

2. A dental or surgical percussion tool com prising: a body; a hammer-armature mounted for reciprocation on said body; solenoid coil means for reciprocatingsaid hammer-armature; an anvil and tool tip positioned for engagement by said hammer-armature and mounted for limited reciprocation on said body; a control switch for said solenoid coil means operated by movement of said tool tip relative to said body in response to pressure thereof against a surface; yieldable means between said switch and body adapted to maintain said switch closed during repeated impacts of said hammer-armature and reciprocations of said anvil and tool; means for regulating the frequency of reciprocation of said hammer-armature; and means for regulating the impact force thereof against said anvil.

3. A dental or surgical percussion tool comprising: a body; a hammer-armature mounted for reciprocation on said body; a pair of axially displaced solenoid coils on said body surrounding said hammer-armature; an anvil and tool tip positioned for engagement by said hammerarmature and mounted for limited reciprocation on said body; a switch for directing a supply of current alternately to said solenoid coils to cause reciprocation of said hammer-armature; means for controlling the frequency of operation of said switch; means for regulating the kinetic energy imparted to said hammer-armature thereby to regulate the impact force delivered to said tool tip; a control switch for said solenoid coils operated by movement of said tool tip relative to said body in response to pressure thereof against a surface; and means to maintain said control switch closed during repeated impacts on said tool tip and reciprocations of said anvil and tool.

4. A dental or surgical percussion tool, as set forth in claim 3 wherein: said frequency controlling means involves an electro-magnetic means for actuating said switch; an electron discharge device; and adjustable means for causing said device to pass current periodically thereby to energize' said electro-magnetic means.

5. A dental or surgical percussion tool, as set forth in claim 3 wherein: said frequency controlling means involves a cam means for controlling said switch; and a variable speed motor for driving said cam.

'6. A dental or surgical percussion tool, as set forth in claim 3 wherein: said frequency controlling means involves a vibrating member for actuating said switch; electro-magnetic means connected with said switch to vibrate said member, and means for adjusting the frequency of vibration of said member.

7. A dental or surgical percussion tool comprising: a tube; a hammer-armature reciprocable in said tube; a solenoid coil surrounding said tube; an anvil mounted for limited movement in one end of said tube; a rotatable internally threaded member surrounding the other end of said tube; 'a traveler nut slidable axially in said tube and engageable with said rotatable member, said nut forming an adjustable stop forsaid hammer-armature; and a yieldable means interposed between said hammer-armature and said traveler nut.

8. A percussion tool for dentists and surgeons, involving: a support; an electromagnetic hamassume mer on said support an anvil onv said support and adapted to be engaged bysai-dhammer; and-a tool head including a housing defining an axial bore in alignment with said anvil. and; an angularly related bore; a percussion pin in said axial bore operatively associated with said anvil; a tool tip having a shank; reciprocable in said angular bore, said shank having a lateral recess for receiving an end of said pin; and mating impact surfaces in said recess and at, the end of said pin for transmitting the impact of said anvil to said tool tip.

9. A dental or surgical percussiontool comprising: a body; a hammer-armature mounted for reciprocation on said body; .a pair of axially displaced solenoid coils adapted for alternate operation thereby to reciprocate said hammerarmature; an anvil and tool tip mounted for limited reciprocation on said body and positioned for engagement by said hammer-armatme; a switch for controlling said solenoid coils operatively connected with said anvil by a lost-motion means; yieldable means urgingsaid anvil in a direction to hold said switch open, said yieldable means being responsive to a predetermined pressure against said tool tip to close-said switch; and means for maintaining said switch closed irrespective of movement of saidanvil in response to impact of said hammer-armature.

10. A dental or surgical percussion tool com prising: a support; a hammer-armature reciprocable on said support; solenoid coil means-for reciprocating said hammer-armature; an anvil and tool tip mounted for movement on said; support and positioned for engagement by said hammer-armature; a control switch for Said solenoid coil means responsive to movement of said tool tip relative to said support when pressed against a surface to receive an impact; and means for varying the tool tip pressure required to actuate said switch.

11. A dental or surgical percussion tool comprising: a support; a hammer-armature reciprocable on said support; a pair of axially displaced solenoid coils alternately operable thereby to reciprocate said hammer-armature; an anvil and tool tip moveably positioned on said support for engagement by said hammer-armature; a switch for directing a supply of current alternately to said solenoid coils; means for controlling the frequency of operation of said switch; means for regulating the kinetic energy imparted to said hammer-armature thereby to regulate'the impact force delivered to said tool tip;.a control switch for said solenoid coil means responsive to movement of said tool tip relative to said support when pressed against a surface to receive an impact; and means for varying the tool tip pressure required to actuate said switch.

12. A dental or surgical percussion tool. comprising: a support including a tube; a pair of tandem disposed solenoid coils surrounding said tube; means for alternatingly energizin said solenoid coils; a freely floating hammer-armature reciprocable in said tube upon alternate operation of said coils; a movable tool assembly on said support and having an anvil and extending into one end of said tube for impact engagement by said hammer-armature; a bumper spring mounted in said tube at the end opposite from said anvil; and means for adjusting the position ofsaid. Spring to yieldably limit the stroke of said hammer-armature.

13. -A dental or surgical percussion tool, comprising: a tube; a pair of tandem disposed solenoid coils surrounding said tube; means for alternatingly energizing said solenoid coils; a freely floating hammer-armature reciprocable in said tube upon alternate operation of said coils; a tool assembly having an anvil end positioned for impact engagement by said hammer-armature; a first spring tending to extend said assembly and adapted to be opposed by external pressure exerted against the extended end of said assembly; a switch unit for said solenoid coils normally held open by said first spring, said switch being in position to be engaged by said assembly and closed by movement of said assembly in response to pressure at its extended end; and a second spring subservient to said first spring tending to maintain said switch closed during repeated impacts of said anvil against said assembly and the resulting movement thereof.

14. A dental or surgical percussion tool comprising: a body structure; electromagnetic means in said body structure and including a reciprocable hammer-armature, and a control switch having a movable element; a tool assembly carried by Said body structure and including an anvil at its inner end engageable by said hammerarmature, a tool tip at its outer end, a lost-motion device connecting said assembly with the movable element of said switch, and a main spring urging said tool tip to an extended position and normal- -ly maintaining said switch in an open position, said main spring being responsive to predetermined pressure exerted against said tip to yield whereby said assembly may move to close said Switch.

15. A dental or surgical percussion tool comprising: an anvil unit having an impact receiving end and a tool holder end; a switch element connected with said anvil unit by lost-motion means and movable thereby between an open and a closed position, said lost-motion means permitting a predetermined limited movement of said anvil unit while said switch remains in its closed position; yieldable means urging said anvil unit to a position in which said switch is open, an electromagnetic means in circuit with said switch and including a reciprocable hammerarmature positioned to engage said anvil means.

FRED M. HUFNAGEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 170,129 Strohm Nov. 16, 1875 171,121 Green Dec. 14, 1875 368,948 Helmer Aug. 30, 1887 574,025 Edgecomb Dec. 29, 1896 1,449,908 Guckin et a1. Mar. 27, 1923 1,467,677 Lake Sept. 11, 1923 1,954,029 Stansbury Apr. 10, 1934 

